We propose to initiate a study of the regulated expression of the individual members of the collagen gene family and their role in development. We will isolate specific hybridization probes for type I procollagen by the technique of cDNA cloning. These will be used to identify and isolate genes for other members of the collagen family from vertebrate DNA. A set of defined type-specific hybridization probes will be generated from these recombinant molecules. Application of DNA sequencing methods will allow determination of the primary sequence of different procollagen genes and identification of control elements. The specific hybridization probes will permit quantitation of procollagen messenger RNA biosynthesis. Other postulated intracellular mechanisms which might modulate collagen synthesis could then be examined. Collagens are important connective tissue proteins whose synthesis is highly regulated during development. Aberrant collagen synthesis is implicated in several inherited disorders and in environmentally correlated disease states such as atherosclerosis and lung fibrosis.